I played a very successful great plains monarch map with Alexander (Having 4 cows, horses, wheat, AND iron in my capital lowered the actual difficulty to noble I think!).
Anyway, I managed to get pyramids and run representatin early and had basically a SE, but as I always do with a SE, I set up many cottages but nonetheless kept my science slider low. By the time I got pacifism, I adopted it to really hammer out great people, and the large army I was running never became a problem (although I mitigated this a bit with vassalage; those free units are now twice as possible). Additionally, I got a double shrine in my great person farm... which along with I think 4 settled great merchants was pretty sweet for income... especially once wall street was built next to my national epic.
So basically, it worked very well in that situation. I had at least 4 cities that had relatively early cottages (probably founded between 500 BC and 500 AD; this was a raging barbs map and that slowed down settlement), and those cities still maanged to run the mandatory two scientists per city. However, given my luck with the starting position and then also getting a double holy city in my GP farm, this was as close to ideal as things can get, so I'm not sure that it's a great example... anyway...
I think the mot generally applicable thing I learned from trying to have an aggressive pacifist is that vassalage is almost a must-have. It probably brings in more money than the bonus commerce in the capital from beauracracy would because of lowered army maintenance and it also makes your soldiers come out better (since you've already ruled out theocrazy).